Actually, they are an essential tool for any school. While suspensions and expulsions can be abused by an overzealous or over-controlling school administration at times, there are simply some students who's presence at school is too disruptive for everyone else.
In addition, not having suspensions or expulsions as options for student punishment creates a situation where some students are much more likely to break rules and, sadly, to intimidate and disrespect faculty.
None of my students would ever call me a rules Nazi, but these options have to be available for a school to effectively function.
Yes, they should, unfortunately. A school district must have the right to suspend or expel students whose behavior violates those regulations that are in place to protect the lives and well being of all students. Individual rights are important in our society, but a student loses his right to attend school when he or she engages in behavior that infringes upon the rights of other students: the right to attend school in safety and the right to learn in an orderly classroom, without fear.
School districts have very clear discipline policies in regard to suspensions and expulsions, and students are informed of the policies. Students are not suspended or expelled casually or at the whim of an angry administrator. Suspensions, and especially expulsions, are treated as serious matters because they are. Students don't lose their right to attend school unless their conduct is so extreme that it must be addressed with extreme measures.
While very few educators or administrators are not enthusiastic about suspension or expulsion as a discipline method, there are instances when a suspension or expulsion must be embraced. If a child poses an immediate threat to themselves or others, suspending or expelling the child might be an appropriate alternative. After multiple interventions to curb student misbehavior, suspending or expelling the child might help to bring to light to the child that their actions must be curbed. There are some instances when a suspension or expulsion is automatic. For example, if a child brings a weapon to school or engages in an elaborate and premeditated endeavor to hurt another child. This can only be met with the severity of removing that child from the classroom and school setting. Any quality administrator would be able to outline the policy and indicate which offenses merit suspension or expulsion, so that it is not a knee jerk or reactive response to student action.